Theresa May is set to trigger Britain's exit from the EU as early as Tuesday next week as Labour peers indicated they were ready to pass her Brexit bill.
A senior Labour source told Sky News there was an "80 to 90% chance" that the EU Notification of Withdrawal Bill would clear the upper chamber by midnight on Monday, paving the way for the Prime Minister to formally trigger Article 50.
On Monday, the House of Commons is expected to vote down two amendments added to the Brexit bill by peers, with the Government insistent that the legislation be passed unamended.
It will then be passed back to the House of Lords, where there is little appetite to challenge the Commons again on the legislation.
One Labour peer told Sky News that such a move would be too "politically risky". However, another source cautioned that the way David Davis responded to the amendments in the House of Commons on Monday was crucial.
"If he treats the House of Lords with disrespect, it won't be straightforward," said the source. "If he ignores the Lords' amendments and concerns then the 10% comes into play."
The swift passing of legislation would give the Prime Minister the power to formally trigger Article 50 on Tuesday when she updates MPs on last week's EU Council summit.
However, some European sources remained sceptical that the Prime Minister would go for such a tight timetable, given that she would risk a diplomatic upset by triggering Article 50 immediately before the Dutch elections on Wednesday.
William Cash, a leading Brexiteer, told Sky News it might be more "tactful" for Mrs May to wait until the actual polling day to trigger Article 50 in order to avoid the appearance of interfering in the Dutch election.
Geert Wilders, the leader of the far right Party for Freedom, has hailed Britain's vote to leave the European Union as a "patriotic spring" during his election campaign, and could try to turn Britain's Article 50 moment to his advantage in the final hours of campaigning.
Downing Street has committed to triggering Article 50 by the end of March but has refused to give a date.
The House of Lords passed the Brexit bill back to the Commons last week with two amendments: one guaranteed the rights of EU citizens to remain in the EU while the second called on the Government to give parliament a "meaningful vote" on the final deal.
However, David Davis, the Brexit secretary, on Saturday warned colleagues not to support either amendment amid rumours that up to 20 Tory MPs could rebel on the second amendment.
"I will be asking MPs to send the legislation back to the House of Lords in its original form so that we can start building a global Britain and a strong new partnership with the EU," said Mr Davis.
"By a majority of four to one, MPs passed straightforward legislation allowing the Government to move ahead with no strings attached."
Meanwhile, European leaders are also preparing for formal Brexit negotiations to begin within days and have pencilled in a gathering to respond to Britain's formal letter of notification.
Enda Kenny, Ireland's prime minister, told reporters the EU 27 had provisionally set a meeting in early April to agree a framework for exit talks.
He said: "The next meeting is to be on 6 April, provided that the (British) prime minister (Theresa May) moves Article 50, I think by 15 March.
"There will be a response immediately from the European Council, and there will be guidelines issued by the European Council within 48 hours. And the European Council meeting to adopt those guidelines will be on 6 April."
On Friday, Keir Starmer, the shadow Brexit secretary, and Baroness Smith, shadow leader of the House of Lords, wrote to the Prime Minister urging her to "reflect and reconsider on the overwhelming case to act" on the two amendments tabled by peers.
:: Sky Presenter Sophy Ridge will be interviewing shadow Brexit secretary Keir Starmer and Business Secretary Liam Fox from 10am this morning on Sky News.